1. Field of the Invention
The present invention relates to a method for manufacturing a nonaqueous electrolyte secondary cell and to a cell assembly before the initial charging which is for constructing the cell.
The present application claims priority to Japanese Patent Application No. 2015-153691 filed on Aug. 3, 2015, the entire contents of which are hereby incorporated by reference.
2. Description of the Related Art
In a nonaqueous electrolyte secondary cell such as a lithium ion secondary cell, part of the nonaqueous electrolytic solution is decomposed during the initial charging, and a protective coating film (Solid Electrolyte Interface film (SEI film)) including the decomposition products is formed on the surface of a negative electrode. This SEI film stabilizes the interface of the negative electrode and the nonaqueous electrolytic solution and improves cell durability (for example, cyclic characteristic). Japanese Patent Application Publication No. 2011-187440 is a prior art literature relating to such a film. For example, Japanese Patent Application Publication No. 2011-187440 indicates that by introducing a fluoro acid salt into a nonaqueous electrolytic solution, it is possible to form a SEI film including a component derived from the fluoro acid salt on the surface of a negative electrode and improve the durability of a cell.